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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Avaliação do tempo de vida cronológico em Saccharomyces cerevisiae em diferentes fontes de carbono associadas com o metabolismo e com os mecanismos de reparação de DNA

Barea, Fernanda 05 December 2008 (has links)
Uma dieta rica em carboidratos aparece como um dos poucos fatores ambientais capazes de interferir tanto na longevidade quanto no envelhecimento de um organismo. Neste sentido, a geração aumentada e o acúmulo dos AGEs (do inglês Advanced glycation end-products), formados por reações não enzimáticas entre os monossacarídeos glicose e frutose e/ou seus intermediários metabólicos com os ácidos nucleicos e grupos amina de proteínas, determinam a importância que estes produtos representam para a duração do ciclo de vida dos organismos. Os AGEs aparecem associados a uma série de patologias relacionadas com a longevidade e com a ocorrência do envelhecimento precoce, aparecendo em número aumentado nos casos de diabetes melito e nas doenças neurodegenerativas como o Alzheimer e o Parkinson. Nesta dissertação de mestrado buscou-se mostrar uma associação entre as proteínas do metabolismo de carboidratos e as vias de reparação do DNA. Os dados obtidos evidenciaram uma importante interação entre as principais enzimas do metabolismo de carboidratos com as proteínas de reparação de DNA e mostraram que ambos parecem ser essenciais para a manutenção da integridade genômica em leveduras. Nesta dissertação também foi verificado o tempo de vida cronológico de diferentes linhagens da levedura Saccharomyces cerevisiae frente a diferentes fontes de carbono e os resultados obtidos foram relacionados com a atuação do metabolismo de carboidratos e com as vias de reparação do DNA. Soma-se ao trabalho os dados de idade cronológica associados com a ausência do complexo Tor1 (Target of Rapamycin), uma via relacionada com a indução de autofagia e que está associada com os mecanismos promotores da longevidade e do envelhecimento. Os dados gerados por esta dissertação também permitiram relacionar informações importantes sobre o metabolismo de carboidratos e sua interferência nos mecanismos genéticos e bioquímicos associados com a longevidade e com o envelhecimento de leveduras, abrindo caminhos para a realização de novos estudos que visem buscar maiores conhecimentos sobre a caracterização dos mecanismos genéticos associados com a longevidade dos organismos. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-22T17:00:00Z No. of bitstreams: 1 Dissertacao Fernanda Barea.pdf: 625512 bytes, checksum: 6e37386b24cc1eb8e2338a52150f535d (MD5) / Made available in DSpace on 2014-05-22T17:00:00Z (GMT). No. of bitstreams: 1 Dissertacao Fernanda Barea.pdf: 625512 bytes, checksum: 6e37386b24cc1eb8e2338a52150f535d (MD5) / A diet rich in carbohydrates is one of the few environmental factors capable of interfering in longevity and in an aging of organisms. In this sense, the increased generation and/or accumulation of AGES (Advanced glycation end-products) formed by reactions between monosaccharides glucose and fructose and/or their metabolic intermediates with nucleic acid and amine group of proteins determine the importance of these products for the lifespan. The AGES appear to be associated with a series of diseases related with longevity and aging. In addition, it has been reported an increased in AGEs in diabetes mellitus and neurodegenerative diseases, e.g. Alzheimer´s and Parkinson´s diseases. In this work we search for an association between carbohydrate metabolism and DNA repair mechanisms. The data showed a significant interaction between key enzymes of carbohydrates metabolism with DNA repair mechanisms and indicated that both processes seems to be essential for the maintenance of genomic integrity in yeast. In this work it was also verificated the chronological lifespan (CLS) in several strains of yeast Saccharomyces cerevisiae grown on different carbon sources. The results generated were related with carbohydrate metabolism and DNA repair mechanisms. In addition, CLS was associated with the absence of Tor1 (Target Of Rapamycin), a genetic mechanism that has been associated with aging and longevity. Furthermore, the data generated by the current study allowed to obtain important data about carbohydrate metabolism and its association with longevity and the aging of yeast.
32

Contribuciones hacia la cronología del Periodo Arcaico en las punas de Junín

Kaulicke, Peter 10 April 2018 (has links)
Some Contributions to the Chronology of the Archaic Period in the Punas of JunínThe stratigraphy and the typology from the Uchkumachay excavations are presented as well as preliminary results of a comparative study undertaken in collaboration with D. Lavallée and M. Julien. These data bear major importance on the building of a general chronology and synthesis of the Archaic Period which still is missing for the Junín area in spite of being one of the best studied areas in the Central Andes for the time period in question. / La estratigrafía y tipología de Uchkumachay, Junín, están presentadas así como los resultados preliminares de un estudio comparativo entre Uchkumachay y Telarmachay en colaboración con D. Lavallée y M. Julien. Estos resultados tienen mayor importancia para la formación de una cronología general del Periodo Arcaico en el área de Junín la cual es una de las áreas mejor estudiadas de los Andes Centrales durante este periodo pero que aguarda aún una síntesis general y la presentación más completa de los datos disponibles.
33

Avaliação do tempo de vida cronológico em Saccharomyces cerevisiae em diferentes fontes de carbono associadas com o metabolismo e com os mecanismos de reparação de DNA

Barea, Fernanda 05 December 2008 (has links)
Uma dieta rica em carboidratos aparece como um dos poucos fatores ambientais capazes de interferir tanto na longevidade quanto no envelhecimento de um organismo. Neste sentido, a geração aumentada e o acúmulo dos AGEs (do inglês Advanced glycation end-products), formados por reações não enzimáticas entre os monossacarídeos glicose e frutose e/ou seus intermediários metabólicos com os ácidos nucleicos e grupos amina de proteínas, determinam a importância que estes produtos representam para a duração do ciclo de vida dos organismos. Os AGEs aparecem associados a uma série de patologias relacionadas com a longevidade e com a ocorrência do envelhecimento precoce, aparecendo em número aumentado nos casos de diabetes melito e nas doenças neurodegenerativas como o Alzheimer e o Parkinson. Nesta dissertação de mestrado buscou-se mostrar uma associação entre as proteínas do metabolismo de carboidratos e as vias de reparação do DNA. Os dados obtidos evidenciaram uma importante interação entre as principais enzimas do metabolismo de carboidratos com as proteínas de reparação de DNA e mostraram que ambos parecem ser essenciais para a manutenção da integridade genômica em leveduras. Nesta dissertação também foi verificado o tempo de vida cronológico de diferentes linhagens da levedura Saccharomyces cerevisiae frente a diferentes fontes de carbono e os resultados obtidos foram relacionados com a atuação do metabolismo de carboidratos e com as vias de reparação do DNA. Soma-se ao trabalho os dados de idade cronológica associados com a ausência do complexo Tor1 (Target of Rapamycin), uma via relacionada com a indução de autofagia e que está associada com os mecanismos promotores da longevidade e do envelhecimento. Os dados gerados por esta dissertação também permitiram relacionar informações importantes sobre o metabolismo de carboidratos e sua interferência nos mecanismos genéticos e bioquímicos associados com a longevidade e com o envelhecimento de leveduras, abrindo caminhos para a realização de novos estudos que visem buscar maiores conhecimentos sobre a caracterização dos mecanismos genéticos associados com a longevidade dos organismos. / A diet rich in carbohydrates is one of the few environmental factors capable of interfering in longevity and in an aging of organisms. In this sense, the increased generation and/or accumulation of AGES (Advanced glycation end-products) formed by reactions between monosaccharides glucose and fructose and/or their metabolic intermediates with nucleic acid and amine group of proteins determine the importance of these products for the lifespan. The AGES appear to be associated with a series of diseases related with longevity and aging. In addition, it has been reported an increased in AGEs in diabetes mellitus and neurodegenerative diseases, e.g. Alzheimer´s and Parkinson´s diseases. In this work we search for an association between carbohydrate metabolism and DNA repair mechanisms. The data showed a significant interaction between key enzymes of carbohydrates metabolism with DNA repair mechanisms and indicated that both processes seems to be essential for the maintenance of genomic integrity in yeast. In this work it was also verificated the chronological lifespan (CLS) in several strains of yeast Saccharomyces cerevisiae grown on different carbon sources. The results generated were related with carbohydrate metabolism and DNA repair mechanisms. In addition, CLS was associated with the absence of Tor1 (Target Of Rapamycin), a genetic mechanism that has been associated with aging and longevity. Furthermore, the data generated by the current study allowed to obtain important data about carbohydrate metabolism and its association with longevity and the aging of yeast.
34

Cross-regional analysis of population aging in the Arctic

Emelyanova, A. (Anastasia) 16 November 2015 (has links)
Abstract Despite the greater strategic importance and increasing activities in the Arctic as well as the increased attention paid by national governments, few attempts have been made to understand the on-going demographic changes from a pan-Arctic perspective. In particular, population aging or “silverization” is a demographic megatrend affecting regional societies and the economy which can exert profound social consequences in this most desolate and least populated region in the world. Although there are a few studies investigating aging in the Arctic countries, none have extended their research to the sub-national level. This thesis consists of an analysis of aging and possible rejuvenation trends in 23 Arctic sub-regions, and compares these trends to the national average of their eight respective countries. Two groups of indicators have been used to measure aging; these are based on “chronological” and “prospective” ages, the latter considers changes in life expectancy and improvements in population health. The study generated a large set of aging data for the period 1980/1990 to 2010 as well as the present day, utilizing the available baseline data. The discussion examined major trends in aging elucidating the interactions of conventional and prospective indicators, revealed the oldest and youngest territories, linkages between the Arctic and nationwide rates, the fastest and slowest regions that are aging (or in contrast, rejuvenating), sex and ethnic differences, and whether Northern Canada and Alaska, North Atlantic, Arctic Russia and Northern Fennoscandia are converging or diverging in terms of aging development. In addition, the interplay of causes of aging and other demographic conditions of Arctic territories was examined as well as the gaps in knowledge and prospects for future research. The international comparative evidence of the thesis can help the northern communities’ policy makers in planning changes that have to be made in order to adjust to an aging transition. It is clear that sustainable population development is the key to a viable Arctic region. / Tiivistelmä Arktisella alueella tapahtuvaa väestörakenteen muutosta ja sen syitä on tutkittu vähän, vaikka alueen merkitys ja aktiviteetit ovat korostuneet valtioiden strategioissa. Erityisesti väestön ikääntyminen tai ”harmaantuminen” on yleinen demografinen suuntaus, joka vaikuttaa pohjoisten alueiden väestöön ja talouteen ja voi johtaa syvällisiin yhteiskunnallisiin seurauksiin tällä maailman harvaan asutuimmalla alueella. Ikääntymistä on tutkittu jonkin verran yksittäisissä maissa, mutta ei näiden maiden pohjoisissa osissa. Tässä väitöskirjatyössä analysoidaan ikääntymistä ja mahdollista nuorentumista kahdeksan arktisen maan 23 pohjoisella alueella ja näitä verrataan saman maan kansalliseen keskiarvoon. Ikääntymisen mittareina on käytetty kahta mittaustapaa perustuen joko ”kronologiseen” tai ”prospektiiviseen” ikään, joista jälkimmäinen huomioi muutokset odotettavissa olevassa eliniässä sekä väestön terveydentilan kohentumissa. Tutkimuksen tuloksena syntyi laaja ikääntymistä käsittelevä tietoaineisto vuosilta 1980/1990 vuoteen 2010/nykypäivään perustuen käytettävissä oleviin lähtöaineistoihin. Tässä työssä yksilöitiin ikääntymisen pääsuuntaukset ja vertailtiin perinteisten ja uusien indikaattoreiden tuottamia tuloksia. Lisäksi selvitettiin ikääntymisen kannalta väestöltään vanhimmat ja nuorimmat alueet, verraltiin arktisen alueen ja kansallisten lukujen välisiä yhteyksiä sekä esiteltiin nopeimmin ja hitaimmin ikääntyvät (tai nuorentuvat) alueet sekä sukupuoleen ja etnisyyteen liittyviä eroja. Tutkimus luo uutta tietoa Pohjois-Kanadan ja Alaskan, Pohjois-Atlantin alueen, Venäjän arktisen alueen sekä pohjoisen Fennoskandian väestöjen ikääntymiskehityksestä. Lisäksi väitöskirjatyö analysoi ikääntymiskehityksen ja muiden väestökehitykseen liittyvien olosuhteiden syitä arktisella alueella sekä tulevaisuuden tutkimustarpeita. Kansainvälinen vertailu voi auttaa valtioiden ja alueiden päättäjiä tekemään suunnitelmat, joilla pohjoiset yhteisöt voivat sopeutua ikääntymisen tuomiin haasteisiin. Kestävä väestökehitys on avain elinvoimaiseen arktiseen alueeseen.
35

La représentation des bijoux féminins dans l'art de l'Egypte romaine : une classification chronologique / The representation of female jewelry in the art of Roman Egypt : a chronological classification

Michaelis, Lucas 30 November 2013 (has links)
Dans le cadre de ce doctorat sur la représentation des bijoux féminins dans les portraits de l’Égypte romaine, les recherches se concentraient sur les « portraits du Fayoum » et masques funéraires des trois premiers siècles après J.-C.Bien que les masques funéraires et les portraits du Fayoum aient été le sujet de plusieurs publications pendant ces dernières années, il nous manquait encore une étude détaillée sur les bijoux féminins qui s’inspiraient presque exclusivement de la mode romaine. Une classification chronologique de ces portraits, mais aussi des masques funéraires, pouvait être obtenue par les coiffures féminines. Par conséquence, la distinction des portraits par époque nous permettait d’identifier les changements dans la mode des bijoux pendant les trois premiers siècles après J.-C., en donnant aux archéologues la possibilité de classifier encore mieux certains types de bijoux qui sont découverts pendant des fouilles ou sur le marché de l’art. Dans le cadre ce cette étude, les diverses représentations de bijoux, en provenance d’autres provinces romaines mais aussi des originaux, appartenant à des trésors et à des tombes datés étaient également consultés. L’application de nos résultats à d’autres contextes géographiques est toujours légitime, car les mêmes principaux types de bijoux étaient utilisés dans tout l’empire romain.Grâce à toutes ces données, il était possible de reconstruire les différents aspects de la mode des bijoux pour les différentes dynasties impériales pendant les trois premiers siècles après J.-C. / This particular PhD research project focuses on the representation of jewellery on “Fayum portraits” and mummy masks from Roman Egypt. Even though Roman mummy masks and the so called “Fayum portraits” have been the subject of numerous research in recent years, a detailed study on the individuals’ jewellery is still missing up to this date. This is particularly regrettable because females on these portraits are almost exclusively wearing Roman-type jewellery. A chronological order that includes a precise dating must be obtained by the female hairstyles that have been influenced by Roman fashion dispersed in the Roman Empire through representations in form of busts, coins and paintings of the Empresses and members of the imperial families. Consequently, this chronological order allows us to identify the various changes in the jewellery fashion throughout the imperial dynasties of the first three centuries A.D. A goal of the chronological classification of jewellery in the art of Roman Egypt is to help future researchers to date jewellery more precisely, in particular – which is quite common for jewellery - when their provenance is unknown or imprecise. The results will be complemented by representations of jewellery in art from other regions of the Empire but also by actual dated finds. Finally, all these factors will help to obtain a better understanding of Roman jewellery fashion, its distribution and even more which types were “à la mode” at what particular time.
36

Les feldspaths comme support pour la datation par luminescence de gisements archéologiques et de séquences quaternaires d'Aquitaine / Feldspars as support for the luminescence dating of archaeological deposits and quaternary sequences of Aquitaine

Frouin, Marine 12 December 2014 (has links)
Les données chronologiques disponibles pour les gisements du Paléolithique moyen du Sud-Ouest de la France font état d’un manque de jalons chronologiques fiables. Pour ces périodes anciennes, l’établissement d’un cadre chronologique nécessite un investissement méthodologique important dans le domaine de la datation numérique. Les résultats obtenus dans cette étude reposent essentiellement sur la datation par luminescence optique de grains de feldspaths et de quartz contenus dans les sédiments. En particulier, l’étude des signaux de luminescence classiquement exploités (IRSL, pIR-IRSL), nous permet de mieux évaluer la fiabilité des datations à partir des feldspaths potassiques. Un protocole de datation fondé sur l’exploitation du signal de radioluminescence (IR-RF) de ces minéraux a aussi été développé. Ainsi, la luminescence optique a été appliquée à des échantillons provenant de six gisements de référence : Les Pradelles (Marillac, Charente), Combe Brune 2 (Creysse, Dordogne), Roc de Marsal (Campagne, Dordogne), Artenac (Saint-Mary, Charente), La Quina (Gardes-le-Pontaroux, Charente) et La Ferrassie (Savignac-de-Miremont, Dordogne). La combinaison des résultats obtenus nous a permis, au sein de chaque niveau archéologique, d’évaluer la pertinence des datations et de proposer pour chaque gisement un scénario chronologique qui nous semble fiable. À l’issue de cette étude, les occupations humaines, caractérisées selon leurs industries, ont pu être replacées sur une échelle des temps en regard des variations paléoclimatiques et paléoenvironnementales régionales. Plusieurs constats ont été dressés enrichissant le registre de nos connaissances sur les cultures néandertaliennes. / Currently available chronological information for Middle Palaeolithic sites in southwestern France precludes the establishment of a robust chronological framework. For these early periods, developing such a framework relies upon important methodological advancements in numerical dating techniques. The results of this study are essentially based on the optical luminescence dating of sedimentary feldspars and quartz. Focusing on the most commonly employed luminescence signals (IRSL, pIR-IRSL), it was possible to more clearly evaluate the reliability of dates obtained on K-feldspars. A dating protocol for these materials based on their radioluminescence signal (IR-RF) was also developed. Optical luminescence dates were produced for six major archaeological sites: (Marillac, Charente), Combe Brune 2 (Creysse, Dordogne), Roc de Marsal (Campagne, Dordogne), Artenac (Saint-Mary, Charente), La Quina (Gardes-le-Pontaroux, Charente) et La Ferrassie (Savignac-de-Miremont, Dordogne). Collating the results for each archaeological level allowed the coherence of the dates to be tested and a reliable chronological sequence to be proposed for each site. The different human occupations, characterised by their industrial attribution, could be placed within a chronological framework that incorporates regional palaeoenvironmental and palaeoclimatic variations. Finally, several observations provide new insights for our understanding of Neandertal cultures.
37

Características de carcaças bovinas obtidas por frigoríficos na região central do Brasil, um retrato espacial e temporal / Beef carcass characteristics from meat industries in the central region of Brazil, a spatial and temporal picture

Rafael Ferreira Soria 30 September 2005 (has links)
As características de carcaças bovinas relacionam-se indiretamente com aspectos de qualidade da carne bovina, bem como permitem verificar limitações e progressos do sistema produtivo. Portanto, um retrato atual daquelas características em âmbito regional e suas variações anuais e plurianuais é ferramenta essencial na transferência de informação para o gerenciamento e sustentabilidade da cadeia de carne bovina. A análise do banco de dados de um grupo frigorífico com unidades industriais localizadas no Sudoeste de Mato Grosso do Sul, Meio-Oeste de São Paulo, Noroeste de Goiás e Triângulo Mineiro, importantes regiões para a pecuária nacional, durante 31 meses de operação industrial (janeiro de 2001 a agosto de 2003), permitiu descrever as características das carcaças bovinas nessas regiões geográficas, entre épocas do ano e entre os anos. Cada unidade foi abastecida principalmente por fornecedores do próprio estado e as regiões que mais negociaram estavam nas proximidades das unidades, exceto a unidade frigorífica de SP onde grande parte do abate teve origem no Leste de MS. As fêmeas totalizaram 13,16% dos abates e houve oferta crescente no período a partir do segundo semestre de 2002 com pequena redução no abate de machos, destes 75,96% eram castrados e 10,88% inteiros. A região teve impacto na oferta de características como classe sexual, maturidade e grau de acabamento para machos castrados, contudo houve um padrão predominante em todas as unidades em volume e freqüência de oferta, com carcaças de machos castrados de 6 a 8 dentes compondo 61,6% dos abates do grupo. A unidade de GO foi a que mais abateu machos inteiros, totalizando 36% dos abates. A unidade de MG se destacou na proporção de machos castrados até 4 dentes (novilhos) em relação aos machos castrados abatidos, com uma média de 25%. O abate de novilhos com grau de acabamento 3 (espessura de gordura entre 3 e 6 mm) representaram 7,9% dos abates, destacando-se MS e SP em volume de abate e proporção, com 2/3 dos novilhos atingindo este acabamento. A oferta de carcaças de novilhos e de novilhos com grau de acabamento 3 ocorreu em dois momentos do ano, de abril a junho e de agosto a novembro. No período estudado, a oferta de novilhos com grau de acabamento 3 não acompanhou a oferta de novilhos, variando com a região, sendo que a unidade de SP foi abastecida de forma mais regular. O peso médio de abate dos machos castrados foi de 264,4 kg (DP ± 15,2 kg), equivalente a 17,6@ e à medida que os animais avançaram na idade aumentou a freqüência de carcaças pesadas. Carcaças acima de 18@ corresponderam à 40,6% dos adultos e 22,9% dos novilhos. Para os novilhos com acabamento 3 a faixa de peso predominante foi de 16 –17@ em todas unidades, exceto em MG onde a classe de peso predominante esteve acima de 18@. / Beef carcass characteristics are indirectly related with meat quality and helps to identify limitations and progresses of the productive system. Wherefore establishing a picture of such characteristics and their annual and pluriannual variations represents an essential tool on information transference for the beef supply chain management and sustainability. This study was based on data from a beef industry composed by four unities located in important Brazilian regions for beef cattle production (Southeast of Mato Grosso do Sul State, Middle-West of São Paulo State, Northwest of Goiás State and at Triângulo Mineiro Region of Minas Gerais State), during 31 months (January, 2001 to August, 2003). Database analysis allowed to describe beef carcass characteristics within periods over a year and among years of industrial activity. Producers from regions close to the plants inside the same state were their main suppliers, except for the unity in the São Paulo State where a large number of animals came from East of Mato Grosso do Sul State. Castrated males represented 75.96% of total slaughter, intact males 10.88% and females 13.16%. The number of female slaughtered increased over the second semester of 2002 reducing thus the proportion of male slaughtered. There was an influence of the supplying region on sexual condition, maturity and finishing of castrated males with up to four permanent incisors (steers). However, the main carcass pattern in all unities, when considering number and frequency, was castrated males with at least six permanent incisors, representing 61.6% of total slaughter. The Goiás State’s plant slaughtered the highest number of intact males with 36% of its total slaughter. The Minas Gerais State’s plant registered the highest proportion of steers when considering castrated male slaughtered, averaging 25% of its total. Steers with finishing grade 3 (fat thickness 3 to 6 mm) represented 7.9% of all carcasses, distinguishing Mato Grosso do Sul and São Paulo States’ plants in which two-thirds of steers reached that finishing grade. The supply of steers finishing grade 3 had two peaks with increasing offer over the years, from April to July and from August to November. The number of these carcasses did not follow steers supply with a regional influence. São Paulo State plant was the only one regularly supplied with properly finished steers. The average carcass weight was 264.4 kg (SE ± 15.2 kg). Heavier carcasses were obtained only when animals slaughtered grew older with frequencies of carcass weight over 269.9 kg corresponding to 40.6% of the older castrated males and 22.9% of the steers. The most frequent carcass weight ranged from 240 to 254.9 kg for steers with finishing grade 3 in all plants, except for the one at Minas Gerais State where the predominant weight range was over 269.9 kg.
38

Diagrammes et théorie de la relativité restreinte : une ingénierie didactique / Diagrams and special theory of relativity : a didactic engineering

Moutet, Laurent 30 November 2016 (has links)
Nous avons développé et mis à l’épreuve des activités utilisant un registre basé sur des diagrammes lors de l’enseignement de la théorie de la relativité restreinte avec des élèves de terminale S. L’approche graphique est source de difficultés didactiques mais les potentialités didactiques peuvent être plus avantageuses. Une étude épistémologique sur les diagrammes utilisables en relativité restreinte permet de voir les liens importants entre les mathématiques et la genèse de la théorie. C’est le cas du diagramme de Minkowski. Nous avons également étudié les diagrammes de Brehme et de Loedel, créés beaucoup plus tard pour des raisons didactiques. Après les séances pilotes, nous avons développé un nouveau cadre théorique, permettant d’analyser plus finement les interactions développées par les élèves résolvant un problème utilisant des diagrammes en relativité restreinte. Nous avons modifié les espaces de travail mathématique (ETM) en rajoutant le cadre de rationalité de la physique à celui des mathématiques. Le cadre des ETM étendu nous a permis de concevoir plusieurs versions de séquences et de réaliser une analyse a priori de leur niveau de difficulté et a posteriori en étudiant des travaux d’élèves. L’analyse du travail de groupes d’élèves a été effectuée lors d’une séquence utilisant le diagramme de Minkowski avec GeoGebra, un logiciel de simulation graphique. Le degré de maitrise du diagramme de Minkowski a été évalué pour chaque élève du point de vue des mathématiques et de la physique. Les résultats sont prometteurs, ils montrent une appropriation réelle des concepts de la théorie de la relativité restreinte via une approche utilisant des diagrammes. / We tried to develop and test several activities using a register based on diagrams for teaching the special theory of relativity to S class of twelfth graders. The graphic approach may result it complications in learning. However, its educational potential can turn out to be more beneficial. An epistemological study on diagrams used in special relativity allowed us to report important links between mathematics and the genesis of the special theory of relativity. This is the case of the Minkowski diagram. We were also interested in two other diagrams, Brehme and Loedel, which were developed much more later for teaching purposes. Following experimental sessions, we developed a new theoretical frame to comprehensively analyse the interactions developed by students to solve a problem using diagrams in special relativity. We modified the mathematical working spaces (MWS) by adding a new frame of rationality to the existing mathematic workspace to physics. The extended frame of the MWS allowed us to plan several versions of sequences proposed to the students and realize a priori analysis of their difficulty level and a posteriori study by analysing pupils' works. We have considered several works of student groups during a sequence using the Minkowski diagram with GeoGebra, a graphic simulation software. It allowed us to estimate the degree of control of the Minkowski diagram for every student, both from the frame of rationality of the mathematics and the physical sciences’ point of view. The results are promising and they tend to show a real appropriation of the concepts of the special theory of relativity with an approach using diagrams.
39

Reliability assessment of electrical power systems using genetic algorithms / Reliability assessment of electric power systems using genetic algorithms

Samaan, Nader Amin Aziz 15 November 2004 (has links)
The first part of this dissertation presents an innovative method for the assessment of generation system reliability. In this method, genetic algorithm (GA) is used as a search tool to truncate the probability state space and to track the most probable failure states. GA stores system states, in which there is generation deficiency to supply system maximum load, in a state array. The given load pattern is then convoluted with the state array to obtain adequacy indices. In the second part of the dissertation, a GA based method for state sampling of composite generation-transmission power systems is introduced. Binary encoded GA is used as a state sampling tool for the composite power system network states. A linearized optimization load flow model is used for evaluation of sampled states. The developed approach has been extended to evaluate adequacy indices of composite power systems while considering chronological load at buses. Hourly load is represented by cluster load vectors using the k-means clustering technique. Two different approaches have been developed which are GA parallel sampling and GA sampling for maximum cluster load vector with series state revaluation. The developed GA based method is used for the assessment of annual frequency and duration indices of composite system. The conditional probability based method is used to calculate the contribution of sampled failure states to system failure frequency using different component transition rates. The developed GA based method is also used for evaluating reliability worth indices of composite power systems. The developed GA approach has been generalized to recognize multi-state components such as generation units with derated states. It also considers common mode failure for transmission lines. Finally, a new method for composite system state evaluation using real numbers encoded GA is developed. The objective of GA is to minimize load curtailment for each sampled state. Minimization is based on the dc load flow model. System constraints are represented by fuzzy membership functions. The GA fitness function is a combination of these membership values. The proposed method has the advantage of allowing sophisticated load curtailment strategies, which lead to more realistic load point indices.
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Historien längs tuvor och slingriga vägar : En jämförande studie av tematisk och kronologisk undervisning i historia för gymnasieskolan / History along the hummocks and winding roads : A comparative study of thematic and chronological teaching of history in secondary schools

Pettersson, Dan January 2013 (has links)
In the following study the author compares two methods of teaching history, the thematic approach and a more traditional chronological approach. Aiming at distinguishing the perceived notions of strength and weaknesses of each method, from the perspective of teaching, the author uses semi-structural interviews with four teachers in order to shed light on the reasons why each method is chosen. The perceptions of the thematical and chronological method in teaching history are further compared with the result in students’ grades. The result shows that the thematic method is perceived as being better at teaching the student about causality and different understandings of changes in history, which would have positive impact on higher grades. However it was also looked upon as being more demanding of previous knowledge for the student. Therefore teachers would choose the chronological approach if they saw that the necessary previous knowledge was lacking in the class. The grades of different classes showed however that the perceived relation between method and learning can’t be confirmed, but that great difference in grades where found among classes of the same method. Even if the classes of the thematic method shows slightly higher grades then the classes of the chronological method it might be the result of difference in previous knowledge among classes which motivates the choice of method, more than it is the result of the method itself.

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